Which of the following is not a restriction endonuclease?

Options

A. Eco RI
B. Hind III
C. Pst I
D. DNAse I

Answer

To determine which of the given options is not a restriction endonuclease, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Restriction Endonucleases**:
- Restriction endonucleases are enzymes that cut DNA at specific recognition sites, which are usually palindromic sequences. They are primarily found in prokaryotes and serve as a defense mechanism against viral DNA.

2. **Identify the Options**:
- The options provided are:
- A) EcoR1
- B) PST-1
- C) DNA-1
- We need to analyze each option to see if it qualifies as a restriction endonuclease.

3. **Analyze Each Option**:
- **EcoR1**: This is a well-known restriction endonuclease that cuts DNA at a specific site. It is commonly used in recombinant DNA technology.
- **PST-1**: Similar to EcoR1, PST-1 is also a restriction endonuclease that recognizes specific DNA sequences and cuts them.
- **DNA-1**: This is known as deoxyribonuclease, which is an enzyme that degrades DNA but does not have the specificity of restriction endonucleases. It is not derived from prokaryotic organisms and does not function in the same manner as restriction enzymes.

4. **Conclusion**:
- Based on the analysis, the enzyme that is not a restriction endonuclease is **DNA-1**. Therefore, the correct answer is option **C) DNA-1**.